Projection mapping is often a very complicated process due to the careful alignment of projectors required to align numerous two-dimensional (“2D”) projected images onto a three-dimensional (“3D”) surface. Hence, the pose of each of the projectors relative to the surface needs to be calibrated, which is often performed using cameras acquiring images of the physical object as a projector is projecting calibration patterns (e.g. structured light patterns) onto the surface. For example, the structured light patterns generally comprise a series of binary patterns that enable the position of projector pixels to be found on the surface. In particular, images of the structured light patterns on the surface, captured by a camera, may be compared with the actual structured light patterns to determine a geometry of the projectors with respect to the surface and/or the geometry of the surface. However, the structured light patterns are usually projected “off-line”, for example in advance of a show of images projected onto the surface. Hence, this can waste time prior to the show. Furthermore, if the projector and surface move relative to each other after calibration, for example during the show, the projected images may be ruined as they may no longer be aligned with the surface; hence, structured light patterns may again have to be projected off-line to again perform a calibration, thereby interrupting the show.